The Hematopathology Fellowship has been highly successful in attracting outstanding applicants and in providing them with training in hematopathology, emphasizing outstanding clinical diagnosis, and specialized diagnostic tools including molecular diagnostics and flow cytometry. The fellowship has been ACGME accredited since 2000, and graduating fellows have had a nearly a 100% first time pass rate on the accrediting examination given by the American Board of Pathology. Graduating fellows have gone on to establish independent careers in academic medicine, including appointments in recent years at Duke University, Northwestern University Medical Center, Moffit Cancer Center, Children's National Medical Center, University of Chicago, Weill Cornell Medical School), City of Hope National Medical Center, The Mayo Clinic, Memorial Sloan Kettering Cancer Center, Henry Ford Hospital, University of California -San Francisco Medical Center, and the Cleveland Clinic. Four recent graduates have successfully competed for independent NIH RO1 funding. Fellows are encouraged to participate in clinical research; representative publications by trainees over the past year are noted below. Dr. Tapan Bhavsar reported two cases of Kaposi sarcoma-associated herpesvirus (KSHV)-and Epstein-Barr Virus (EBV) associated germinotropic lymphoproliferative disorder, a very rare and poorly understood condition. Both cases arose in patients from regions endemic for KSHV, Cape Verde, and the Democratic Republic of the Congo, presenting as localized lymphadenopathy. Dr. Yi Xie reported the bone marrow findings in autoimmune lymphoproliferative disorder. Autoimmune lymphoproliferative syndrome is a rare genetic disorder characterized by defective FAS-mediated apoptosis, autoimmune disease, accumulation of mature T-cell receptor alpha/beta positive, CD4 and CD8 double-negative T cells and increased risk of lymphoma. Despite frequent hematologic abnormalities, literature is scarce regarding the bone marrow pathology in autoimmune lymphoproliferative syndrome. She retrospectively reviewed 3l bone marrow biopsies from a cohort of 240 patients with germline FAS mutations. All biopsies were performed for the evaluation of cytopenias or to rule out lymphoma. Clinical information was collected and morphological, immunohistochemical, flow cytometric and molecular studies were performed. Bone marrow lymphocytosis was the predominant feature, present in 74% (23/31) of biopsies. The lymphoid cells showed several different patterns of infiltration, most often forming aggregates comprising T cells in 15 cases, B cells in one and a mixture of T and B cells in the other seven cases. Double-negative T cells were detected by immunohistochemistry in the minority of cases (10/31; 32%); significantly, all but one of these cases had prominent double-negative T-lymphoid aggregates, which in four cases diffusely replaced the marrow space. One case showed features of Rosai-Dorfman disease, containing scattered S-100+ cells with emperipolesis and double-negative T cells. No clonal B or T cells were detected by polymerase chain reaction in any evaluated cases. Classical Hodgkin lymphoma was identified in three cases. These results demonstrate that infiltrates of T cells, or rarely B cells, can be extensive in patients with autoimmune lymphoproliferative syndrome, mimicking lymphoma. A multi-modality approach, integrating clinical, histological, immunohistochemical as well as other ancillary tests, can help avoid this diagnostic pitfall. Dr. Hao Wei Wang reported on the pathological spectrum of Castleman disease and related disorders, clarifying diagnostic concepts and criteria.